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Bleaching
Reduction of natural coloring matter to produce white fabric and must be accomplished with a minimum damage of cotton being bleached.
Objectives of Bleaching
- To impart a pure permanent and basic white effect to the fabric.
- To increase the absorbency of the fabric.
- To produce white finishes
- To make textile material suitable for the subsequent process
Bleaching agent and their classification :
The material by which bleaching is done is called bleaching agent.
There are two types of bleaching agent.
- Oxidizing bleaching agent
- Reducing Bleaching agent
- Oxidizing Bleaching agent : the bleaching agent which fulfills bleaching process by producing unsaturated oxygen is called oxidizing Bleaching Agent
- Reducing Bleaching agent: The bleaching agent which fulfills bleaching process by producing other unsaturated elements rather than oxygen is called reducing bleaching agent.
Some example of two types of bleaching agent
| Oxidizing Bleaching Agent | Reducing Bleaching Agent |
| Hypochlorite (NaOCl) (CaOCl2) | Zinc Dust |
| Bleaching Powder | Stannous Chloride (SnCl2) |
| Hydrogen Peroxide | Sulfur Di.Oxide (SO2) |
| Potassium Dichromate | Ferrous Sulphate (FeSO4) |
| Sodium Chloride (NaCl) | Sodium Hydrosulphate (NaHSO4) |
| Ozone (O3) | Hydrogen Sulphite H2S |
| Potassium Per Manganet K2MnO4 |
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